Suppression of the Fano factor in nanoelectromechanical systems

We analyze the shot noise of a spin-degenerate electronic level coupled to an harmonic oscillator in the presence of relaxation. We show that the electromechanical coupling can induce a suppression of the Fano, factor below the value expected without phonons F = 5/9. Moreover, in the presence of finite relaxation, the Fano factor can be even reduced below 1/2. (C) 2007 Elsevier B.V. All rights reserved.